Background
Mattei was born in 1606, the son of Asdrubale Mattei, Marquis di Giove, and his wife Costanza Gonzaga (of the House of Gonzaga).
Mattei was born in 1606, the son of Asdrubale Mattei, Marquis di Giove, and his wife Costanza Gonzaga (of the House of Gonzaga).
He was a nephew of Ciriaco Mattei and Cardinal Girolamo Mattei. In 1643, Pope Urban VIII issued a papal bull recognising Giove as a Duchy of the Mattei, thus making Girolamo Mattei, Duca di Giove. His bull was issued with the words, affinchè la terra sia adorna al titolo più degno (roughly: that the earth is adorned with those more worthy of title).
He had at least one child, Alessandro Mattei (1670-1729), who inherited his father"s titles.